Metastatic follicular thyroid carcinoma diagnosed by fine needle aspiration cytology: a report of 3 cases.

Background: Follicular thyroid carcinomas (FTCs) usually have a benign clinical course, with an excellent long-term prognosis and a propensity for vascular invasion. The most common sites of metastases are lung and bone. Only a few reports are available on fine needle aspiration biopsy findings from metastatic lesions of FTC.